A438
The battle sorcerer still knows at least 1 spell of 9th level. Since the Domain Access ACF doesn't have a minimum, it swaps that one spell for a Domain spell, as normal. He doesn't learn a new spell at level 19.A battle sorcerer knows fewer spells per spell level than a standard sorcerer. Subtract one spell known from each spell level on Table: Sorcerer Spells Known (to a minimum of one spell per spell level).
Since the battle sorcerer is the base class and Domain Access is the ACF, the ACF modifies battle sorcerer and not vice versa.